SQL For Modeling

Let’s fuckup the cluster! Of course after this operation, the final state of the processes can look like this: The cssd service will not be able to start, because there are no voting disks: OK, so let’s try to stop the cluster services: Now we will have to start CRS in exclusive mode and start […]

I’ve wrote about privilege escalation with external tables in this post: https://blog.ora-600.pl/2014/12/23/simple-technics-of-privilege-escalation-part2-dbasysdba/ This time we will try to list all files within directory object, to which we have no EXECUTE privs. This is possible due to great new feature of database 12c that allows to use metacharacters to match multiple files in external table. I […]

Sorry for long time without post, but we are writing with Marcin Rydz a new heterogenous replication product based on archivelogs and it’s consuming a looooooot of our time 🙂 Yes I know it’s nothing new on the market. There are other cool products and I know they’ll be probably be better. But we want […]

There is a new feature in Oracle Spatial 12c, called "Spatial Vector Acceleration". According to Oracle: One of the most notable improvements with Oracle Spatial and Graph 12c can be seen in performance increases in vector data operations. Enabling the Spatial Vector Acceleration feature (available with the Spatial option) dramatically improves the performance of commonly […]

It’s time for the next article with ODBV visualisation 🙂 This time let’s examine the difference between move and shrink – this is very common question on a lot of trainings. You can find a lot of great articles in the Internet regarding this subject but I think that visualisation really helps to understand what […]

From time to time I get questions on my trainings, what is the difference between TRUNCATE TABLE and TRUNCATE TABLE DROP STORAGE… well, there is no difference because DROP STORAGE is default 😉 DROP STORAGE Specify DROP STORAGE to deallocate all space from the deleted rows from the table except the space allocated by the […]

If you work as a consultant, getting remote access to your customer is sometimes a nightmare! Even when you’ll get one, there a times when you just want to get your job done and finish this nightmare. For example, there are times when it is easier to dump a statspack repo and do offline analyzes. […]

I had a pleasure to work with my colleagues from Oracle – Radosław Kut and Krzysztof Marciniak – at comparing the performance of In-Memory queries between Sparc M7, Intel® Xeon® X5670 and Intel® Xeon® E5-2699. You can find results of our findings in this presentation: https://www.oracle.com/webfolder/s/delivery_production/docs/FY16h1/doc17/DB12c-on-SPARC-M7.pdf Following their methodology I’d like to present appropriate results […]

Let’s check, why PRAGMA UDF makes execution faster, then regular function. C function responsible for calling a PL/SQL code from SQL is called "plsql_run": Now let’s try to create a new HR session and create a simple function which will multiple values by 2: From other terminal I will connect to the HR session with […]

Thanks to suggestions made by Frits Hoogland, I made some improvements to the ODBV. The new version can be found here: http://ora-600.pl/oinstall/odbv.x86_64 The changes are: Recognition of first, second and third level bitmap block Recognition of pagetable segment header Block number ranges on the left side The blocks will be coloured properly to belonging segment. […]

Recently I wanted to demonstrate to some people on my training, how Oracle database maintains blocks in a datafile – what happens after truncate, truncate with drop storage clause, delete, regular insert, direct path insert and so on… I didn’t find any tool for that so I’ve written my own. It’s core code is based […]

So we had a doubtful pleasure of migrating a few databases from Oracle Exadata X3-2 to Oracle Exadata X7-2 Cloud at Customer. Why doubtful? Well, this a material for a whole different story with a lot of beer – let me just say, that CC gen 1 was a bit rough around the edges 😉 […]